Abstract: To provide a pressure-sensitive adhesive that is used in processing an article such as a semiconductor wafer that causes neither contamination nor breakage of the semiconductor wafer during the processing, the pressure-sensitive adhesive sheet has a base, an intermediate layer, and a pressure-sensitive adhesive layer in order. The intermediate layer includes a composite film that contains an acrylic-based polymer and a vinyl-based polymer as active ingredients. The urethane polymer contains a component having a weight-average molecular weight of 10,000 or less in a differential molecular weight curve in a content of less than 10%.

Abstract: To provide a pressure-sensitive adhesive that is used in processing an article such as a semiconductor wafer, the pressure-sensitive adhesive sheet is one that has a base, an intermediate layer and a pressure-sensitive adhesive layer in order, wherein the intermediate layer has an elastic modulus at elongation at 23° C. of 1 MPa or more and 100 MPa or less, the intermediate layer includes an acrylic polymer obtained by polymerization of a (meth) acrylic monomer mixture containing 1% by weight or more and 20% by weight or less of a nitrogen-containing acrylic monomer, the acrylic polymer containing 20% by weight or less of a polymer component having a molecular weight of 100,000 or less, and the base includes at least one film having an elastic modulus at in tension at 23° C. of 0.6 GPa or more.

Abstract: To provide a pressure-sensitive adhesive sheet, which is used in processing an article such as a semiconductor wafer, the pressure-sensitive adhesive sheet has a base, an intermediate layer and a pressure-sensitive adhesive layer in this order, wherein the intermediate layer has an elastic modulus in tension at 23° C. of 10 MPa or more and 100 Mpa or less, the intermediate layer includes an acrylic-based polymer obtained by polymerization of a mixture containing 70 to 99 parts by weight of a (meth)acrylate monomer and 1 to 30 parts by weight of an unsaturated carboxylic acid based on 100 parts by weight of total monomers, and the base includes at least one film having an elastic modulus in tension at 23° C. of 0.6 GPa or more.

Abstract: To provide a pressure-sensitive adhesive sheet used during processing articles such as semiconductor wafers and laminate sheet used for such a pressure-sensitive adhesive sheet, which does not contaminate or break the semiconductor wafers during the processing and can minimize the curl of the articles due to residual stress of the pressure-sensitive adhesive sheet, a multi-layer sheet includes a composite film containing a urethane polymer and a vinyl-based polymer as effective components and a first film made of a material different from that of the composite film, wherein the urethane polymer is formed from a polyolefin diol and a polyisocyanate. A pressure-sensitive adhesive sheet is obtained by providing a pressure-sensitive adhesive layer on at least one side of the multi-layer sheet.

Abstract: The present invention provides a pressure sensitive adhesive composition for optical members, which is excellent in durability, re-releasability and stress relaxation, as well as a pressure sensitive adhesive composition for optical members, which hardly increases adhesion after storage for a long time and does not leave a residual adhesive on glass upon disposal or repair. The pressure sensitive adhesive composition for optical members according to the present invention comprises 100 parts by weight of an acrylic polymer (A) having a weight-average molecular weight of 500,000 or more, containing at least 50 wt % alkyl (meth)acrylate having an alkyl group with 5 or more carbon atoms and 0.2 to 2 wt % unsaturated carboxylic acid as the monomer unit, 0.